An analyzer is known from DE-A-19 21 302 in which trays equipped with cuvettes are moved along a feed path and past a processing station. The trays are provided with slots cooperating with a feed mechanism. Also a mechanical latching means engages with said slots in order to fix a cuvette exactly in the processing station. Due to its many mechanical components, this known analyzer is of a complex design and operates awkwardly.
More specifically, the problem addressed by the invention centers around tolerances of the tray and of the probe that has to pick up pipette tips in the tray. In order for the tray to be an inexpensive disposable, it is necessary that the tips be carried in apertures in the tray that are so loosely dimensioned as an inside diameter, compared to the outside diameter of a held tip, that the tips are likely to slide horizontally within the apertures to the extent that they will not properly line up with the probe, even when the tip in question is nominally located at the station for probe pickup. That is, the apertures provide such a degree of sliding tolerance (are so much larger than the held tips' outside diameter) that as the tips are carried to the probe station, they will end up displaced out of vertical alignment with the probe, beyond the degree of displacement that the probe can tolerate. As a result, some mechanism is needed to realign the slid tips, and this invention addresses that problem.